A pulsed ECR ion source: environmental and beam-induced background suppression

Matthew Buckner, University of North Carolina

At TUNL’s Laboratory for Experimental Nuclear Astrophysics (LENA), we have been exploring several methods of pulsing the LENA Electron Cyclotron Resonance (ECR) ion source. Remote, LabVIEW-controlled, pulsed proton-beam operation has been extended to the LENA ECR Ion Source by pulsing the extraction high voltage power supplies. Experimental limitations are introduced for low-energy nuclear astrophysics reactions because the Coulomb barrier reduces nuclear reactions rates significantly. As a result, environmental and cosmic-ray backgrounds often dominate the signal. Pulsing the beam on target introduces a method of reducing these environmental backgrounds.

Beam induced backgrounds are another factor we must take into consideration. Impurities such as 11B, 12C, 15N and 19F occur naturally in our tantalum target backings. Etching and out-gassing target backings cut from ultra-high purity tantalum should introduce a significant reduction in beam-induced backgrounds.

The steps we are taking towards environmental and beam-induced background suppression should enhance our ability to perform low-energy experiments relevant to nuclear astrophysics. We will utilize these methods to investigate key low-energy reactions that have not been studied previously or can be improved upon—the resonance strength of the EP = 95 keV resonance of 18O(p,γ)19F and direct capture of 17O(p,γ)18F in the classical nova Gamow peak (Ep = 103-261 keV). Latest results will be reported.

Abstract Author(s): M. Q. Buckner, J. M. Cesaratto, T. B. Clegg and C. Iliadis [1, 2][1] Triangle Universities Nuclear Laboratory, Durham, NC and the University of North Carolina at Chapel Hill, Chapel Hill, NC[2] Supported in part by US DOE and DOE NNSA SSGF